Field of the Invention
The present disclosure relates to message processing. In particular, but not exclusively, the present disclosure relates to processing multicast group membership discovery protocol messages in a data center network.
Description of the Related Technology
Multicast group membership discovery protocols such as the internet group management protocol (IGMP) or the multicast listener discovery (MLD) protocol are designed for internet protocol (IP) networks where potentially there are a large number of subscribers on the same local area network (LAN). IGMP for example assumes that the network in which it is deployed has a tree topology with end receivers at the bottom of the tree and a multicast data source at the top of the tree. On a given LAN, each IGMP-speaker (i.e. an entity which understands the IGMP) is either a router or a host or both. An IGMP host multicast requests for data by sending an IGMP Report onto the LAN. Such a Report can be thought of a request in the form of “please send me data from source S2 to group G2” for example.
All IGMP routers in the LAN receive such requests and the routers elect which router is designated to forward traffic onto the LAN from amongst themselves. The underlying assumption is that any router can receive any data from upstream. A router can then act as a Proxy to forward Reports upstream (or to request data from an upstream node using some other means).
Some networks do not have a tree topology and not all IGMP routers are guaranteed to be able to receive traffic from an upstream source. In these cases, IGMP will not always operate correctly. Such issues can arise in relation to IGMP and internet protocol version 4 (IPv4) and also in relation to MLD and internet protocol version 6 (IPv6). It would therefore be desirable to provide improved measures for processing multicast group membership discovery protocol messages, including in networks which do not have tree (or tree-like) topologies.